1. Field of the Invention
The present invention relates to a fuzzy inference circuit, and more particularly, to a fuzzy inference circuit using a charge coupled device.
2. Discussion of the Related Art
A conventional fuzzy inference circuit will be described with reference to the accompanying drawings.
FIG. 1 is a configuration block diagram of a conventional fuzzy inference circuit. FIG. 2 is a configuration block diagram of a fuzzy rule memory using conventional digital logic.
Referring to FIG. 1, a conventional fuzzy inference circuit includes a control object 1, a sensor 2, an analog to digital (A/D) converter 3, a clock generator 4, a fuzzy rule memory 5, a fuzzy inference engine 6, and a digital to analog (D/A) converter 7.
The sensor 2 senses a state of the control object 1, and transfers the sensed value of the control object 1 to the A/D converter 3. The A/D converter 3 converts an analog signal of the sensor 2 to a digital signal.
The fuzzy rule memory 5 stores fuzzy rule function values through digital logic. The fuzzy inference engine 6 receives a clock signal generated from the clock generator 4 in order to perform a fuzzy inference using the fuzzy rule function values and the digitized sensed value in a well-known manner. The D/A converter 7 converts a digital signal from the fuzzy inference engine 6 to an analog signal to control the control object 1.
Referring to FIG. 2, the fuzzy rule memory 5 includes a first memory 8, a second memory 9, a comparator 10, a selector 11, and a third memory 12.
The first and second memories 8 and 9 store fuzzy rule function values. The comparator 10 compares the fuzzy rule function values from the first and second memories 8 and 9 with each other to output their comparative value to the selector 11. The selector 11 selects either the fuzzy rule function value from the first memory 8 or the fuzzy rule function value from the second memory 9 in response to a selective signal S input from the comparator 10, and transfers the selected value to the third memory 12. The third memory 12 transfers the fuzzy rule function value transferred from the selector 11 to the fuzzy inference engine 6.
Referring to FIG. 1, fuzzy inference engine 6 receives the clock signal from the clock generator 4, the digital signal from the A/D converter 3 and the fuzzy rule function values from the fuzzy rule memory 5, and performs a fuzzy inference on the sensed value using the fuzzy rule function values according to an operational timing established by the clock signal. The fuzzy inferred value from the fuzzy inference engine 6 is converted to an analog value through the D/A converter 7, and supplied as a control value to the control object 1.
The conventional fuzzy inference circuit has a problem in that additional memories such as the first, second and third memories are required to store a digital value when the fuzzy inference is performed using a digital circuit. In addition, since an analog signal is input and output, the A/D converter and the D/A converter are additionally required. For this reason, the conventional fuzzy inference circuit has disadvantages such as high cost and slow process speed.